Display screen or portion thereof with transitional graphical user interface



FIG. 1 is the first image in a sequence of a display screen or portion thereof with transitional graphical user interface showing my new design;

FIG. 2 is the second image thereof;

FIG. 3 is the third image thereof;

FIG. 4 is the fourth image thereof;

FIG. 5 is the fifth image thereof;

FIG. 6 is the sixth image thereof; and,

FIG. 7 is the seventh image thereof.

The dot-dash broken line in FIGS. 2-7 defines the boundaries of the claimed design and forms no part thereof. The dashed broken line perimeter in the figures illustrates a display screen or portion thereof and forms no part of the claimed design. The remaining dashed broken lines in the figures illustrate portions of the graphical user interface that form no part of the claimed design.

The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-7. The process or period in which one image transitions into another image forms no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 